IN2017_C02 Bass Strait Bathymetry 10m - 210m Multi-resolution AusSeabed products

This layer group describes multibeam echosounder data collected on RV Investigator voyage IN2017_C02 titled "RAN Hydrographic Survey". The voyage took place between May 4 and May 15, 2017, departing from Hobart (TAS) and arriving in Bell Bay (TAS).\n\nThe purpose of this voyage was to gain an understanding of the nature of the marine environment in the survey area and to collect meteorological and oceanographic data in the area to contribute to current modelling systems. \n\nThis dataset is published with the permission of CSIRO. Not to be used for navigational purposes.\n\nThe dataset contains bathymetry grids of 10m to 210m resolution of the Bass Strait produced from the processed EM122 and EM710 bathymetry data.\nLineage: Multibeam data was logged from the EM’s in Kongsberg’s proprietary *.all format and was converted to be processed within Caris HIPS and SIPS version 10.2.1\nOnce converted, tidal data was loaded, TPU computed and the data merged.\nSurfaces were generated using the CUBE BASE surface algorithm within Caris. Rather than a traditional line by line cleaning approach followed by full subset cleaning a directed editing approach was undertaken. The coverage of each MBES system was analysed and a number of filters applied to the data as described below:\n1. A broad ‘depth-gate’ to filter out any erroneous soundings.\n2. In the case of the EM2040c an across track filter was used to reject soundings outside of a 400m swath width.\n3. TPU filtering to reject any soundings that do not meet IHO Order 1A criteria.\n4. A surface filter to reject any soundings that lay more than 2σ (95%) from the mean.\nThe data was reviewed in subset and only soundings that negatively impacted the CUBE surface were further rejected.\n\nThe data was then gridded at multiple resolutions in python Caris batch script using a Depth filter Vs Resolution guideline derived from AusSeabed Multibeam guidelines v2 and further inspected for outliers. Final raster products are available in L3 folder of this collection. Final processed data were also exported per line as GSF and ASCII format and available in the L2 folder of this collection.

本图层组描述了由RV Investigator（调查者号研究船）执行的IN2017_C02航次所采集的多波束测深仪（multibeam echosounder）数据，该航次主题为"RAN Hydrographic Survey（RAN水文调查）"。本次航次于2017年5月4日至5月15日期间开展，从塔斯马尼亚州霍巴特（Hobart, TAS）起航，最终抵达塔斯马尼亚州贝尔贝（Bell Bay, TAS）。

本次航次的目的在于探明调查海域的海洋环境特征，并采集该海域的气象与海洋学数据，为现有数值模拟系统提供支撑。

本数据集经澳大利亚联邦科学与工业研究组织（CSIRO）许可发布，不得用于导航用途。

本数据集包含基于经处理的EM122与EM710测深数据生成的巴斯海峡（Bass Strait）水深栅格数据，栅格分辨率覆盖10米至210米区间。

数据溯源：多波束数据由康士伯（Kongsberg）公司的EM系列测深仪以其专有格式*.all记录，并转换为可在Caris HIPS与SIPS 10.2.1版本中处理的格式。格式转换完成后，加载潮汐数据，计算TPU（Tidal Processing Unit），并完成数据合并。

水深表面模型通过Caris软件内的CUBE BASE表面算法生成。本次处理未采用传统的逐航线清洗后全子集清洗的流程，而是采用了定向编辑方案。对每套多波束测深系统（MBES, Multibeam Echosounder System）的覆盖范围进行分析，并对数据应用如下多种滤波处理：
1. 采用宽幅"深度门限"过滤所有错误测深点。
2. 针对EM2040c测深仪，采用航迹向滤波剔除400米条带宽度以外的测深点。
3. TPU滤波，剔除不符合国际海道测量组织（International Hydrographic Organization, IHO）1A类标准的测深点。
4. 表面滤波，剔除与均值偏差超过2σ（95%置信区间）的测深点。

对数据进行子集复查，仅剔除那些对CUBE表面模型产生负面影响的测深点。

随后，基于《AusSeabed多波束指南v2》中提出的水深滤波与分辨率对应规则，通过Python脚本调用Caris批处理工具，将数据以多种分辨率进行栅格化处理，并进一步检查异常值。本数据集的L3文件夹中提供最终栅格产品。经最终处理的单航线数据还以GSF与ASCII格式导出，存放在本数据集的L2文件夹中。